Gas-filled electric lamp



March 18 1924.

- E. J. HUNT GAS FILLED ELECTRIC LAMP Fi led July 10. 1920 INVENTOREDWARD J- HL/NT.

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ATTORNEY Patented Mar. 18, 1924.

UNITED STATES EDWARD JARVIS HUNT, OF NEWARK, JERSEY.

GAS-FILLED ELECTRIC LAMP.

Application filed July 10, 1920. Serial No. 395,255.

To all whom it may concern:

Be it known that I. EDWARD J. HUNT, a citizen of the United States,residing at Newark, in the county of Essex and State of New J ersey,have invented certain new and useful Improvements in Gas-Filled ElectricLamps, of which the following is a specification.

This invention relates to the manufacture and structure of incandescentelectric lamps and particularly to a type in which a refractory filamentis surrounded by an inert gas.

The main purpose of my invention is to prolong the life of the lampfilament by reducing the evaporation of the filament effected by anincreased gas pressure within the lamp bulb. A further object is toprovide a simple and effective method of maintaining the pressure in thebulb as the lamp is being filled and finally sealed. Another object isto provide means for preventing short-circuiting between two main leadsfrom a. deposit on the glass stem adjacent thereto.

The manner in which these purposes are accomplished is set forth in thefollowing description in connection with the accompanying drawings inwhich-Figure 1 is a. longitudinal sectional view of an incandescentelectric lamp embodying my invention; Fig. 2 is a fragmentarylongitudinal section of the same taken in a plane at right anglesthereto; Fig. 3 is a side elevation of one form of the electro-magnetfor holding the ball check valve in the gas inlet; Fig. 4 is a crosssectional view on the line 44 of Fig. 1; and Fig. 5 is a fragmentarysectional view showing the tip of the lamp bulb tubulated and providedwith a magnetically controlled ball check valve.

The lamp bulb or envelope 1 is rovided with a filament 2, mounted as usuupon a glass stem 3 projecting inwardly from the base of the lamp. Isurround the inner ends of the lead wires 6 with tubular glass sleevesor sheaths 8 which are sealed in the flattened portion 3 of the stem.These glass sleeves greatly increase the linear glass surface betweenthe leads on which a deposit must accumulate before an arc-over from onelead to the other can occur.

' The gas inlet tube 9, in the form illustrated in Figs. 1 and 2, passesinwardly from the base through the recess or cavity in the stem andterminates in a port 10 opening into the lamp bulb chamber. The outerportion is contracted to form a seat at 12 tation 13 which serves as astop for the ball.

In this position the ball does not completely close the bore of the tubeand the air may be exhausted from the bulb. Thereafter, when it isdesired to introduce gas into the bulb, the magnet, is deenergized topermit the ball valve to drop down upon the seat 12. Gas under pressuremay then be forced through the tube lifting the valve slightly duringits passage, but cannot escape outwardly since the seating of the valvecompletely closes the tube.

After the bulb has been filled with an inert gas, such as nitrogen orargon, to the desired pressure, the magnet is removed and the tube issealed oil? as indicated at 16, in Fig. 2, the escape of gas during thesealing operation being substantially prevented by the ball check andthere being no pressure beyond the valve to interfere with making theseal.

The walls of the stem are preferably made of heavy glass capable ofwithstanding great gas pressure while the walls of the gas inlet tube orwindpipe 9 are made of glass which is thinner than that of the stem andof the walls of the bulb so that any break which mi ht perchance occurwould take place at t is weakest point, thereby relieving the pressurein the direction of the screw shell 17, which may be provided with aplurality of openings 18 to afford a free escape for the gas.

Instead of exhausting the bulb and introducing the inert as through thebase of the lamp, the tip 0? the bulb may be provided with an exhaustand gas inlet tube 9, as indicated in Fig. 5.

I claim 1. An incandescent electric lam com prising an envelope or bulb,a ament mounted therein, a gas-fill' tubulure adapted to be sealedwithin the amp structure, and a check-valve of magnetic material,

permanently enclosed in the sealed tubulure adjacent the sealing pointand ada ted to automatically close the bore of said tu ulure. 2. A11incandescent lamp, comprising an envelope or bulb, a filament mountedtherein, said envelope bein filled with an inert gas under pressure andhermetically sealed, and a check-valve of magnetic material mountedwithin the envelope and positioned to seat over the sealing point.

3. An incandescent electric lamp, comprising an envelope or bulb, a stemextending inwardly from the lamp base, a filament mounted upon saidstem, a gas-filling tube extending through a portion of said stem andopenlng into the lamp chamber, a checkvalve of magnetic material mountedwithin said tube and adapted to .close the bore thereof when seated,said tube projecting outside of the lamp base to form a connection forexhausting the filament chamber and for filling it with an inert gas,and

means for holding the-valve open durin the "exhausting operation andpermitting itto seat while the tube is being sealed.

In testimony whereof I aflix my signature.

EDWARD JARVIS HUNT.

